GB2440765A

GB2440765A - Track circuit with phase difference adjustment

Info

Publication number: GB2440765A
Application number: GB0704238A
Authority: GB
Inventors: Haruhiko Onuma; Noriharu Amiya; Tamio Okutani; Nobuyuki Nakamura; Mitsuyosi Fukuda; Takahito Matsuki
Original assignee: JRTT JAPAN; Hitachi Ltd
Current assignee: JRTT JAPAN; Hitachi Ltd
Priority date: 2006-08-10
Filing date: 2007-03-05
Publication date: 2008-02-13
Anticipated expiration: 2027-03-05
Also published as: GB2440765B8; GB2440765A8; GB0704238D0; CN101121413A; JP5005289B2; GB2440765B; CN101121413B; JP2008037394A

Abstract

The invention provides higher efficiency signal transmission in a track circuit by minimizing the phase difference between the output voltage and output current of a transmitter and thereby minimizing reactive power and maximizing effective power. A track circuit 1T comprises a transmitter 1 for transmitting a train detection or train control signal to a connected rail 6 and a receiver 10, connected to a reception end of the rail 6, for receiving the signal from the transmission means 1. The transmission circuit comprises a phase adjustment means 2 which adjusts the phase difference between voltage and current of a train detection signal or a train control signal transmitted by the transmitter 1 so as to cause the phase difference to approach 0. The adjustment means may be a transformer 2, having a coil or a capacitor, or both of them added in parallel or in series having an inductance value and capacitance for causing the phase difference between voltage and current of the transmitted signal transmitted by the transmission means 1 to approach 0. A pseudo cable comprising a reactance, a resistor and a capacitor may also be used in conjunction with a transformer having a phase adjuster (Fig 6).

Description

* 2440765

TRACK CIRCUIT

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a track circuit for detecting a train position, and more particularly to a technique for increasing the output efficiency of a transmitter.

Description of the Related Art

In general, track circuits are handled as an electrical circuit. The track circuit includes a transformer, rail and cable; and it has a reactance component and a susceptance component. To perform train detection by a track circuit technique, a train detection signal is transmitted from a transmitter to the track circuit equivalent to an electrical circuit, and then the train detection signal is received via the track circuit by a receiver (refer to Japanese Patent Laid-Open No. 2 005-178614) . Also, to perform train control by the track circuit technique, a signal current flowing in the rail of the track circuit is received as a train control signal through an electromagnetic induction by a pickup arranged on the train. Accordingly, the train detection signal and train control signal must have reception electric power sufficient to ensure train detection performance and train control performance, and must therefore have output electric power sufficient to ensure the above performance.

When an alternating signal is transmitted from the transmitter, the absolute valueof thephase differencebetween output voltage and output current of the transmitter is occasionally increased by a reactance component and susceptance component of the trackcircuitandcable. In this case, a large part of the outputted signal becomes reactive power; as a result, it is difficult to ensure train detection performance and train control performance in a track circuit having a longer rail, a track circuit having a longer cable, or a track circuit having lower signal transmissionperformance, thereby causing a problem.

According to the above described conventional art, when the phase difference between output voltage and output current of the transmitter is large, in order to ensure train detection performance and train control performance, it is needed to increasetheoutputofthetransmitter, ortoshortenthelength of rail in the track circuit, or to shorten the length of cable in the track circuit.

An object of the present invention is to provide higher efficiencysignal transmissioninatrackcircuitbyminimizing the phase difference between output voltage and output current of a transmitter and thereby minimizing reactive power and maximizing effective power.

SUMMARY OF THE INVENTION

To achieve the above object, according to the present invention, a phase adjuster is arranged between a transmitter and cable or between the transmitter and track circuit, or in both the above positions. Using this phase adjuster, the output impedance of transmitter is adjusted to minimize the phase difference between output voltage and output current of the transmitter.

More specifically, according to the present invention, there is provided a track circuit including transmission means for transmitting a signal to a connected rail and reception means, connected to a reception end of the rail, for receiving the signal sent from the transmission means, wherein the track circuit includes adjustment means for adjusting a phase difference between voltage and current of a train detection signal or a train control signal transmitted by the transmission means so as to cause the phase difference to approach 0.

Also, according to the present invention, there is provided the track circuit, wherein the adjustment means includes a transformer having an inductance value for causing the phase difference between voltage and current of the train detection signal or train control signal transmitted by the transmission means to approach 0.

Also, according to the present invention, there is provided the track circuit, wherein the adjustment means includes a transformer, having a coil or a capacitor, or both ofthemaddedinparallelorinseriesintheexteriororinterior thereof, and at the same time having an inductance value and a capacitance for causing the phase difference between voltage and current of the train detection signal or train control signal transmitted by the transmission means to approach 0.

Further, according to the present invention, there is provided the track circuit, wherein the adjustment means adjusts a phase difference between voltage and current of the train control signal transmitted during presence of a train on the rail so as to cause the phase difference to approach 0.

Also, according to the present invention, there is provided the track circuit, wherein the adjustment means adjusts a phase difference between voltage and current of the train detection signal transmitted during absence of a train on the rail so as to cause the phase difference to approach 0.

Also, according to the present invention, there is provided the track circuit further including a pseudo cable composed of a reactance, a resistor and a capacitor, wherein using the pseudo cable, the length of cable is configured so as tobe considered identical to that of another track circuit, and the phase difference between voltage and current is made to approach 0 by use of a transformer having an phase adjuster or an inductance.

According to the present invention, concerning the train detection signal and train control. signal outputted from the transmitter, the phase difference between the output voltage and output current of the transmitter is minimized, whereby reactive power can be minimized and effective power can be maximized, thus allowing higher efficiency signal transmission.

Using such an approach, it is possible to ensure train detection performance and train control performance without increasing the rated output of the transmitter/receiver, or without shortening the length of cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a train detection device according to Embodiment 1; FIG. 2 is a view for additionally explaining Embodiment 1; FIG. 3 is a block diagram of a train detection device according to Embodiment 2; FIG. 4 is a block diagram of a train detection device according to Embodiment 3; FIG. 5 is a block diagram of a train detection device according to a variation of Embodiment 3; and FIG. 6 is a block diagram of a train detection device according to Embodiment 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described.

Embodiments of a track circuit according to the present invention will be described with reference to the drawings.

[Embodiment 11 Embodiment 1 will be explained. A first embodiment of the present invention will be described with reference to FIGS. 1 and2. FIG. 1 is ablockdiagramof a track circuit according tothepresentembodiment. The trackcircuit lTofthepresent embodiment is constitutedof a transmitter 1, a phase adjuster 2, a transformer 3, a cable 4, a transformer 5, a rail 6, a transformer 7, a cable 8, a transformer 9 and a receiver 10.

A train detection signal outputted from the transmitter 1 is received via the track circuit iT by the receiver 10, whereby train detection is performed.

The transmitter 1 outputs a train detection signal fl to the track circuit iT. The transformer 3, cable 4, transformer 5, rail 6, transformer 7, cable 8 and transformer 9 constituting the track circuit iT each have a reactance component and a susceptance component; therefore the whole track circuit iT has a reactance component and a susceptance component. Accordingly, as illustrated in FIG. 2, the train detection signal fi outputted from the transmitter 1 has a phase difference between voltage and current; that is, the absolute value of the output impedance in the track circuit side as seen from the transmitter 1 is Zi and the phase thereof isel. Inthiscase, ofanoutputvoltagePl ofthetransmitter 1, an effective power Pie is calculated by a formula Pie = P1 x cosine ei. When ei is 0, effective power Pie has a maximum value, so phase ei is adjusted by the phase adjuster 2 so as to cause]. to approach 0 or to cause ei to be reduced to a minimum, whereby the train detection signal can be outputted at a maximum effective power or at a substantially maximum effective power.

The phase adjuster 2 is constituted of a coil or a capacitor, or of a coil and capacitor. The inductance value of the coil, or the capacitance of the capacitor of the phase adjuster 2 is varied to adjust the reactance component and susceptarice component of the phase adjuster 2, whereby phase ei of the output impedance of the transmitter 1 is made to approach 0, or minimized. Referring to FIG. 2, the phase adjuster 2 is inserted in series to the track circuit, but the similar effect can be achieved even when inserted in parallel.

it is rioted that, concerning the train detection signal, the phase difference between voltage and current thereof is preferably reduced to a minimum or made to approach 0 during absence of a train on the rail.

[Embodiment 2] Embodiment 2 will be explained. A second embodiment of the present invention will be described with reference to FIG. 3. According to the present embodiment, there is provided a track circuit inwhich, tocause thephasedifferencebetween outputvoltageandoutputcurrentofatransmitterl toapproach o or to be reduced to a minimum, phase adjustment is performed by properly setting the inductance value of a transformer through which a transmitter 1 outputs a signal, whereby the output of the transmitter 1 is optimized.

FIG. 3 is a block diagram of the track circuit according to the present embodiment. The transformer 3 is constituted of a coil. The coil of the transformer 3 has an inductance value; accordingly, when the inductance value of the coil is adjusted, the output impedance of the transmitter 1 can be varied. Thus, the inductance value of the coil of the transformer 3 is set so as to cause the phase difference between output voltage and output current of the transmitter 1 to approach 0, or to be reduced to a minimum. Accordingly, as with Embodiment 1, the train detection signal outputted by the transmitter can be outputted at a maximum effective power or at a substantially maximum effective power. Processes other than this is similar to those of Embodiment 1, and hence an explanation thereof is omitted here.

[Embodiment 3] Embodiment 3 will be explained. A third embodiment of the present invention will be described with reference to FIGS. 4 and 5. According to the present embodiment, the phase adjustment in the track circuit illustrated in Embodiment 1 and Embodiment 2 is optimized during presence of a train on the rail; and the effective power of a train control signal f2 is maximized.

FIG. 4 is ablockdiagramof the trackcircuit illustrated in Embodiment 1, particularly during presence of a train on the rail; FIG. 5 is a block diagram of the track circuit illustrated in Embodiment 2, particularly during presence of a train on the rail. Referring to FIGS. 4 and 5, since a train 11 is present on a rail, the train 11 causes short circuit in the rail 6 and thus the output voltage and output current of a transmitter 1 varies compared to during absence of a train on the rail. Concerning train control signal f2, current flowing in the rail is converted to voltage via a coil arranged at the front of the train 11 through electromagnetic induction, and transferred to a receiver in the train; therefore the currentmusthaveapredeterminedvalueormore. Accordingly, the phase difference between output voltage and output current also varies. Thus, when the phase difference of output impedanceof the transmitter 1 ismade toapproachOorminimized, the rail current of train control signal f2 can be maximized or substantially maximized. Processes other than this is similar to those of Embodiment 1, and hence an explanation thereof is omitted here.

Embodiment 4 will be explained. As illustrated in FIG. 6, a track circuit of the present embodiment includes pseudo cables l2andl3composedofa reactance, resistor andcapacitor.

When the length of cable varies among a plurality of track circuits, if the pseudo cables composed of a reactance, resistor and capacitor are used and the above length of cable is configured so as to be considered identical to that of another track circuit, then electrical performance is uniform among the plurality of track circuits. And the track circuit is configured so that the phase difference between voltage and current is made to approach 0 by a transformer 3 including a phase adjuster or an inductance. Accordingly, using the transformer having a phase adjuster or an inductance and having the same electrical performance, higher efficiency transmission can be achieved also in a track circuit with a cable having a different length.

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Claims

What is claimed is: 1. A track circuit comprising: transmission means

for transmitting a signal to a connected rail; and reception means, connected to a reception end of the rail, for receiving the signal from the transmission means, wherein the track circuit comprises adjustment means for adjusting a phase difference between voltage and current of a train detection signal or a train control signal transmitted by the transmission means so as to cause the phase difference to approach 0.

2. The track circuit according to claim 1, wherein the adjustment means includes a transformer having an inductance value for causing the phase difference between voltage and current of the train detection signal or train control signal transmitted by the transmission means to approach 0.

3. The track circuit according to claim 1, wherein the adjustment means includes a transformer, having a coil or a capacitor, or both of them added in parallel or in series in the exterior or interior thereof, and at the same time having an inductance value and a capacitance for causing the phase difference between voltage and current of the train detection signal or train control signal transmitted by the transmission means to approach 0.

-11 - 4. The track circuit according to any one of claims 1 to 3, wherein the adjustment means adjusts a phase difference between voltage and current of the train control signal transmitted during presence of a train on the rail so as to cause the phase difference to approach 0.

5. The track circuit according to any one of claims 1 to 3, wherein the adjustment means adjusts a phase difference between voltage and current of the train detection signal transmitted during absence of a train on the rail so as to cause the phase difference to approach 0.

6. The track circuit according to any one of claims 1 to 5, wherein comprising a pseudo cable composed of a reactance, a resistor and a capacitor, wherein using the pseudo cable, the length of cable is configured so as to be considered identical to that of another track circuit, and the phase difference between voltage and current is made to approach 0 by use of a transformer having an phase adjuster or an inductance.

7. A rail track circuit substantially as herein described with reference to and as shown in Figs. 1 and 2, Fig. 3, Figs. 4 and 5 or Fig. 6 of the accompanying drawings.

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